The present invention, in some embodiments thereof, relates to structured light sensing generation for 3D sensing and, more particularly, but not exclusively, to a structured light method and apparatus using overlapping patterns of multi-emitters.
Very generally, structured light sensing is the process of projecting a known pattern, such as a grids or horizontal bars, on to a scene. The way that the grid or bars continue or do not continue, deform and displace, when striking surfaces allows vision systems to calculate the depth and surface information of the objects in the scene. Structured light may be used in 3D scanners.
The structured light may often be invisible or imperceptible, thus allowing it to be used without users being aware of its presence.
A component of structured light devices is the creation of a light pattern that is projected onto the scene to be measured in the 3D scanning process. The prior art includes spatially structured light which is generally based on fixed patterns, and temporally structured light which is based on a dynamically changing pattern. The light pattern is created in one of two ways. In a first method a single emitter is projected through a series of optics to create a full pattern. In a second method multiple emitters are imaged or projected through optical elements such that each of the emitters creates part of the pattern.
The use of multiple emitters in the prior art can be divided into several categories. In one category, each one of the emitters is first collimated by a lenslet attached directly to the specific emitter. The far field pattern is then created from the array of collimated beams over the full field of view.
In a second category, a non-regular arrangement of emitters is first projected onto a small part of the far field as is, and then the arrangement is duplicated to cover the large field of view.
In a third category, individual diffractive optical elements are placed in front of each emitter creating a specific part of the far field pattern.